Staphylococcus aureus is an indigenous Gram positive bacterium on the body surface such as the skin and the gastrointestinal surface of the human and animals, and is harmless to the healthy humans, but in the immune-compromised cases such as postsurgical patients, new born infants and elderly persons, they develop various severe infectious diseases such as including from cutaneous soft tissue infection, for example suppurative conditions accompanied by incised wound or penetrating wound to pneumonia, peritonitis, sepsis, cerebral meningitis, and in addition thereto, food poisoning, shock syndrome and enteritis caused by enterotoxin and toxic shock syndrome toxin-1. There are not negligible severe cases and in worst cases cause to death. Recently, methicillin-resistant Staphylococcus aureus (MRSA) is recognized as social problem as a cause for causative microorganisms of in-hospital infection. This pathogenic microorganism is resistant against various drugs such as β-lactam antibiotics, consequently glycopeptide series antibiotic, vancomycin, and aminoglycoside series antibiotic arbekacin are used for treatment of MRSA infection at present. Other antibiotics recently developed such as quinupristin.delfopristin mixture and oxazolidinone antibiotic, linezolid are known.
Vancomycin and arbekacin presently used as the effective antibiotics against MRSA are known to exhibit side effects such as hearing impairment caused by eight cranial nerve disorder. Further, the glycopeptide antibiotic induces side effects such as shock, nephrotoxicity and red man syndrome, and when it is clinically administered, careful administration such as performing blood level monitoring is required. In addition to the multiply-resistant MRSA, low sensitive bacteria against major curative drug vancomycin are reported. Consequently, appearance of novel antibiotics and development of new therapeutic methods are demanded. Actually as the new therapeutic method, a combination therapy with β-lactam antibiotics or β-lactam antibiotic and other antibiotic having different mode of action is on going (Hiromi Hasegawa et al. “Science of antibiotic administration, pp. 264-273, 1998). Further, a substance which does not exhibit antimicrobial activity by itself but has an action to recover or activate an efficacy of β-lactam antibiotics is reported. For example, tea extract or its active fractions (polyphenol compounds) disclosed in the published Japanese translation of PCT international publication for patent application Hei 9-509677 or stemphones (PCT/JP2006/305625) can be mentioned.